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Topic: Gorda Plate


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In the News (Wed 22 May 19)

  
  Gorda Plate -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-22)
The Gorda Plate is a small oceanic (additional info and facts about tectonic plate) tectonic plate beneath the (The largest ocean in the world) Pacific Ocean off the coast of northern (A state in the western United States on the Pacific; the 3rd largest state; known for earthquakes) California.
The subducting Gorda Plate is connected with the (additional info and facts about volcanoes) volcanoes in northern California, namely, (A volcanic mountain peak in the Cascade Range in northern California (14,162 feet high)) Mount Shasta and (additional info and facts about Lassen Peak) Lassen Peak.
The Gorda Plate and the Juan de Fuca Plate, are the last remaining fragments of the (additional info and facts about Farallon Plate) Farallon Plate, along with the (additional info and facts about Cocos Plate) Cocos Plate and (additional info and facts about Nazca Plate) Nazca Plate.
www.absoluteastronomy.com /encyclopedia/g/go/gorda_plate.htm   (296 words)

  
 MSN Encarta - Search View - Plate Tectonics
The theory of plate tectonics was formulated during the early 1960s, and it revolutionized the field of geology.
Early in the plate tectonic revolution, geologists proposed that transform faults were a new class of fault because they “transformed” plate motions from one plate boundary to another.
As a transform plate boundary cuts perpendicularly across the edges of the continental crust near the borders of the continental and oceanic crust, the result is a system such as the San Andreas transform fault system in California.
encarta.msn.com /text_761554623__1/Plate_Tectonics.html   (3862 words)

  
 MSN Encarta - Plate Tectonics
Plate Tectonics, theory of global tectonics (geological structural deformations) that has served as a master key, in modern geology, for understanding the structure, history, and dynamics of the Earth’s lithosphere, which includes the crust.
Although the plate tectonics revolution in geological thought occurred only recently (in the 1960s and 1970s), the roots of the theory were established by earlier observation and deduction.
Where an oceanic tectonic plate is subducted beneath continental crust, the magma produced by subductive melting erupts from volcanoes situated among long, linear mountain chains, such as the Cordillera, up to 100 km inland from the zone of subduction.
uk.encarta.msn.com /encyclopedia_761554623/Plate_Tectonics.html   (1571 words)

  
 Pacific Plate - Wikipedia, the free encyclopedia
The Pacific Plate is an oceanic tectonic plate beneath the Pacific Ocean.
To the north the easterly side is a divergent boundary with the Explorer Plate, the Juan de Fuca Plate and the Gorda Plate forming respectively the Explorer Ridge, the Juan de Fuca Ridge and the Gorda Ridge.
The westerly side is a convergent boundary subducting under the Eurasian Plate to the north and the Philippine Plate in the middle forming the Mariana Trench.
en.wikipedia.org /wiki/Pacific_Plate   (253 words)

  
 Pulling the Rug Out from under California   (Site not responding. Last check: 2007-10-22)
The Gorda plate is being subducted obliquely beneath the North American plate along the "megathrust" of the Cascadia subduction zone.
Plate motion reconstructions based on oceanic magnetic anomalies indicate that the MTJ was initiated 25-29 million years ago when an oceanic spreading ridge collided with the Cordilleran subduction zone.
As the Gorda plate moves to the northeast relative to North America, it leaves in its wake a wedge of North American lithosphere that thins to the west and is underlain by asthenospheric upper mantle.
quakes.coas.oregonstate.edu /papers/mendocino.eos/eos.html   (3214 words)

  
 [No title]   (Site not responding. Last check: 2007-10-22)
The southern Gorda plate is being rotated clockwise as it internally deforms and fragments near the triple junction.
At the triple junction, the pieces of the fragmenting Gorda crust may delaminate from the subducting lithosphere, flow into the slabless window and be annealed to the based of the North America crust by the upwelling asthenosphere.
Perhaps frictionally decoupled from the internally deforming Gorda plate is the overlying accretionary prism and forearc basin.
www.geo.utexas.edu /techtalks/Abstracts/Gulick.doc   (1641 words)

  
 CVO Website - Juan de Fuca Volcanics
The boundary between the Pacific and Juan de Fuca Plates is marked by a broad submarine mountain chain about 500 kilometers long, known as the Juan de Fuca Ridge.
As the denser plate of oceanic crust is forced deep into the Earth's interior beneath the continental plate, a process known as subduction, it encounters high temperatures and pressures that partially melt solid rock.
The Explorer Plate separated from the Juan de Fuca approximately 4 million years ago and is apparently no longer being subducted (Hyndman, et.al., 1979); the Gorda split away between 18 and 5 million years ago (Riddihough, 1984).
vulcan.wr.usgs.gov /Volcanoes/JuanDeFucaRidge/description_juan_de_fuca.html   (1334 words)

  
 Manila Dunes
The collision of the oceanic and the continental plates have caused the coastal landmass to rise rapidly, forming steep mountains (PWA, 1991).
Global plate motion models and the magnetic qualities of the Gorda plate, combined, suggest the rate of convergence between the North American plate and the Juan de Fuca / Gorda plates to be between 2 and 4 cm per year.
The Gorda plate age ranges from 5 ma at the north to 9 ma near the Mtj (Burke and Carver, 1992).
www.humboldt.edu /~jrp2/Documents/dunes.html   (4330 words)

  
 Plate Motions
Notice that the plate motion is NOT orthogonal to the mid-ocean ridge, but at an angle; this will be an important reason why the oceanic plates move northward, causing the "yet-to-be-created" San Andreas fault to lengthen.
Above is the plate reconstruction at 28 m.y., immediately after "first contact" of the ridge and subduction zone.
As soon as the ridge contacts the subduction zone, and the Farallon plate is essentially split into two parts, we redefine the plates as the Juan de Fuca plate (labeled; the northern subduction zone) and the Gorda plate (not labeled; the southern subduction zone).
www.geology.wisc.edu /~g109/Additional/plate_motions.htm   (618 words)

  
 On Shaky Ground 2 Why
The San Andreas fault is the boundary between the Pacific and North American plates; the Mendocino fault separates the Gorda and Pacific plates.
The Cascadia subduction zone is the boundary between the Gorda and Juan de Fuca plates offshore and the North American plate.
North of the triple junction, the Gorda plate and its northern extension, the Juan de Fuca plate, move eastward on a collision course with the North American plate.
sorrel.humboldt.edu /~geodept/earthquakes/shaky2_why.html   (846 words)

  
 Geologic Setting of Mount Shasta
The plates are 100 to 150 kilometers thick, and move slowly across the hotter, softer ASTHENOSPHERE beneath them in response to the tug of sinking ocean lithosphere and thermal circulation in the deeper mantle.
The Cascadia subduction zone is a shallowly-dipping fault that separates the Gorda, Juan de Fuca, and Explorer plates from the overriding North American plate (Figure 4).
The Mendocino fault is a steep shear boundary that separates the Gorda plate, which is moving eastward relative to the underlying mantle, from the Pacific plate which is moving westward.
www.siskiyous.edu /shasta/geo/set.htm   (1069 words)

  
 Solving a geological puzzle / Coast Range between S.F. and Mendocino has long baffled experts   (Site not responding. Last check: 2007-10-22)
Plates are the star players in the theory of plate tectonics, which has dominated geology since the 1960s.
For example, plates that converge or ram together are responsible for the expansive Himalayas, while the still-active volcanoes of the Pacific Northwest are formed by the Juan de Fuca plate subducting under the western North American plate.
He suggested that as hot mantle filled the void left by the retreating Gorda plate, the hot matter cooled and solidified, in effect "welding" the base of the Gorda and North American plates together.
www.sfgate.com /cgi-bin/article.cgi?file=/c/a/2003/10/13/MN262484.DTL&type=printable   (1796 words)

  
 Ozalaybey and Savage, JGR
The correspondence between the fast directions and the present plate tectonic deformations suggest that mapping upper mantle deformation through seismic anisotropy is a viable method, and that asthenospheric flow may be a significant contributor to seismic anisotropy.
The active internal deformation of the Gorda plate was suggested to explain the change in the direction of basement lineations and magnetic anomalies found in the Gorda Basin (e.g., Wilson, 1986, 1989; Stoddard, 1987).
Approximate present boundary of the Gorda plate is shown from Jachens and Griscom (1983) and Severinghaus and Atwater (1989).
www.seismo.unr.edu /htdocs/students/OZALAYBEY/JGR/jgr.html   (7883 words)

  
 Geophysicists map youngest section of San Andreas Fault
The Pacific Plate to the south and the Gorda plate to the north are oceanic plates.
The third boundary is a thrust fault: the Gorda plate thrusts inland under the North American plate, forming the Cascadia subduction zone, the source of earthquake and volcanic hazards in the Pacific Northwest.
For the past 29 million years, the two ocean plates have been slowly moving northward along the edge of the continental plate, grinding out earthquakes; triggering tsunami waves; squeezing hot magma from beneath the crust to feed hot springs, geysers and volcanoes; and forming mountains and valleys and suboceanic canyons.
www.stanford.edu /dept/news/pr/95/951212triplejunc.html   (1219 words)

  
 Is San Francisco's a real earthquake risk?   (Site not responding. Last check: 2007-10-22)
The Gorda plate also moves north, but at the same time it is also moving east, underneath the North American plate.
Recent seismic studies have shown that the crust of the Mendocino Triple Junction is twice as thick as that north and south of the area.
During their study researchers found that as the Gorda plate moves under the North American plate, a void forms at the intersection which allows hot magma to push up.
www.scienceagogo.com /news/19991118191028data_trunc_sys.shtml   (1181 words)

  
 GORDA BASIN EARTHQUAKE, NORTHWESTERN CALIFORNIA
Earthquake epicenters in the region are concentrated along the Blanco fracture zone, the Gorda (spreading) ridge, and the Mendocino fracture zone (east and south of the Gorda Ridge).
Active spreading at the Gorda ridge is in part responsible for the eastward motion of the Gorda plate.
Line with barbs indicates the subduction zone, where the Gorda plate is sliding beneath the North American plate: the barbs are on the overriding plate.
www.johnmartin.com /earthquakes/eqpapers/00000050.htm   (2064 words)

  
 juan_de_Fuca_advanced
This 500km divergent zone (Brantley, 1994) is composed of three major sea mount ridges (the Gorda, Juan de Fuca, and the Explorer ridges) approximately 8km wide (Brantley, 1994) which feed both the Juan de Fuca microplates to the west and the Pacific plate to the east.
This subduction plate is believed to have several strike and dip angles along the curve of the subduction extent.
The shape of the subducting plate at the bend in the subduction zone is an issue of significant controversy.
www.colorado.edu /GeolSci/Resources/WUSTectonics/PacNW/juan_de_Fuca_advanced.html   (934 words)

  
 AGU Web Site:Pulling the Rug out From Under California: Seismic Images of the Mendocino Triple Junction Region
The Gorda plate is being subducted obliquely beneath the North American plate along the"megathrust" of the Cascadia subduction zone.
The top and bottom of the Gorda plate and the position of anomalously strong lower crustal reflectivity south of the triple junction are also shown.
North of the triple junction (Figure 2a), the new data indicate that the crust of the Gorda plate lies above both layers of seismicity: it is about 10 km beneath the deformation front and dips about 7° to the east beneath the continental margin.
www.agu.org /sci_soc/trehu.html   (2816 words)

  
 USA Today (Society for the Advancement of Education): More faults found off West Coast   (Site not responding. Last check: 2007-10-22)
The Pacific Coast from northern British Columbia to Punta Gorda, near Cape Mendocino in California's Humboldt County, is the region known to geologists as the Cascadia Subduction Zone.
The Gorda Plate, about 5,000,000 years old at the point where it enters the subduction zone, is a relatively young, hot, thin plate in geological terms.
The Pacific Plate, south of the Gorda Plate, creeps northward about one inch a year along the California coast, compressing the Gorda Plate and triggering frequent small to moderately sized earthquakes within the plate.
www.findarticles.com /p/articles/mi_m1272/is_2709_132/ai_n6059993   (507 words)

  
 PRELIMINARY STRUCTURE MAP OF THE GORDA "PLATE" FROM MULTIBEAM BATHYMETRY, SIDESCAN SONAR, AND SEISMIC REFLECTION DATA   (Site not responding. Last check: 2007-10-22)
Preliminary structural mapping of the Gorda plate offshore southern Oregon and northern California using multibeam bathymetry, sidescan sonar and seismic reflection data reveals the presence of a substantial number of strike-slip and reactivated spreading-center normal faults.
The northern part of the plate is dominated by long, NNE-trending reactivated spreading fabric normal faults that offset Gorda basin sediments.
Preliminary estimates of slip-rate on a major sinistral strike-slip fault, calculated from approximate offsets observed on the multibeam data and using basement as the maximum age of fault movement, suggests that between 0.5-2 mm/yr of slip may be occurring on structures in the center of the plate.
gsa.confex.com /gsa/2002CD/finalprogram/abstract_35134.htm   (467 words)

  
 Tectonic Evolution of Western North America -- Comments   (Site not responding. Last check: 2007-10-22)
This is a derived rate; that is, the approximate mean rate needed to move the North American plate surface from the California coast to the Colorado Plateau across an assumed stationary zone of upwelling mantle in a period of 30 million years.
Because plates may deform internally, all points on a plate may not have the same motion; however, intra-plate movement should be small relative to inter-plate movement.
Between the Gorda Plate and the Aleutian trench, transform movement between the Pacific and North American plates does not appear to be taking place at a rate similar to displacement on the San Andreas fault.
home.att.net /~cochrans/nawcom01.htm   (1944 words)

  
 Ocean Crust Geochemistry-Mendocino Transform Zone
The Mendocino Transform Fault (MTF) is the major plate boundary between the Gorda Plate and the Pacific Plate in the NE Pacific Ocean.
It is an active zone of dextral strike-slip motion separating 6-8 Ma crust of the Gorda plate from 28-30 Ma crust of the Pacific Plate.
In spite of the age contrast of the two adjacent plates and the expected depth offset, the older, Pacific Plate is elevated up to 1.5 km above the younger Gorda plate.
www.mbari.org /crust/MTZ.htm   (345 words)

  
 USGS Geology in the Parks   (Site not responding. Last check: 2007-10-22)
Where the Juan de Fuca Plate sinks beneath the North American Plate there is no deep trench, seismicity (earthquakes) are fewer than expected, and there is evidence of a decline in volcanic activity over the past few million years.
The small Juan de Fuca Plate and two platelets, the Explorer Plate and Gorda Plate are the meager remnants of the much larger Farallon oceanic plate.
The Explorer Plate broke away from the Juan de Fuca about 4 million years ago and shows no evidence that it is still being subducted.
wrgis.wr.usgs.gov /docs/usgsnps/province/cascade2.html   (514 words)

  
 juan_de_Fuca_general
Toward the end of the Farallon plate portions of the Farallon plate were entirely subducted under the North American plate and the Pacific-North American plate boundary began to dominate the western U.S. The Pacific plate has different characteristics and a different vector (tending NE related to North American plate motion) then the Farallon plate.
The Gorda Plate (the southern most of the three microplates) fractured from the Juan de Fuca plate approximately 18 - 5Ma at the Blanco Fracture Zone (Wood and Kienle, 1990).
This divergent zone is composed of three major sea mount ridges (the Gorda, Juan de Fuca, and the Explorer ridges) which feed both the Juan de Fuca microplates to the west and the Pacific plate to the east.
www.colorado.edu /GeolSci/Resources/WUSTectonics/PacNW/juan_de_Fuca_general.html   (757 words)

  
 geodynamics of mendocino triple junction   (Site not responding. Last check: 2007-10-22)
This process of ephemeral crustal thickening is proposed to result from viscous coupling between the northward migrating Gorda (Juan de Fuca) slab and the base of North America south of the triple junction.
Rapid cooling of emplaced mantle creates a viscous coupling among the exposed edges of the Gorda and Pacific plates and the exposed underside of the North American crust.
Migration of the Gorda plate drives deformation within the North America crust.
www.geodyn.psu.edu /research/americas/egs99/background.html   (213 words)

  
 Mendocino Triple Junction Offshore Northern California
This activity is generated in response to ongoing plate motions between the Gorda, North America, and Pacific plates.
Interaction between the Gorda and Pacific plates occurs as oblique convergence at a rate of approximately 5 cm/year in the direction N115ºE. Translational motion occurs along the east-west-trending, vertical right-lateral Mendocino transform fault.
The Gorda-Pacific convergence results in internal deformation of the Gorda plate, such as the 11/8/1980 Ms7.2 quake, and more recently the two Ms6.6 aftershocks of the 1992 quake.
woodshole.er.usgs.gov /operations/obs/rmobs_pub/html/mendocino.html   (701 words)

  
 Continental Drift and Plate Tectonics
The small plate between the Pacific and North American Plates is called the Gorda Plate.
The plate north of the Pacific Plate is inferred only from the magnetic patterns on the Pacific Plate.
The present Cocos, Nazca and Gorda Plates are its descendants.
www.uwgb.edu /dutchs/platetec/kula.htm   (583 words)

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